Device for collecting the contents of cuvets in a rotating spectrophotometer analyzer

ABSTRACT

Known rotating spectrophotometers have a series of cuvets arranged in a ring member concentrically around a horizontally rotatable disc so that when the disc is rotated, centrifugal force mixes and transfers reagents and samples to the cuvets. As each cuvet passes a light source, the absorbence of each individual sample is detected and measured photometrically, and is converted to an electrical signal pulse. Upon completion of the measurements it is necessary to empty the cuvets and it is important that dispersion of the cuvet contents be avoided to prevent unsanitary and otherwise undesirable conditions. This is accomplished in the present invention by forcing the contents of the cuvets into a concave ring shaped member attached to the cuvette ring where the expelled liquid is held and confined.

United States Patent Martin Apr. 2, 1974 DEVICE FOR COLLECTING THECONTENTS OF CUVETS IN A ROTATING SPECTROPHOTOMETER ANALYZER [75]Inventor: Sterling T. Martin, Charleston, W.

[73] Assignee: Union Carbide Corporation, New

York, NY.

[22] Filed: Sept. 22, 1972 [21] Appl. No.: 291,282

[52] US. Cl. 233/26, 356/197 [51] Int. Cl B04b 7/00 [58] Field of Search233/26, 27, 28, 46, 47 R, 233/17; 23/259 R; 356/197 [56] ReferencesCited UNITED STATES PATENTS 3,547,547 12/1970 Anderson 356/197 2,688,4379/1954 Monnet 233/46 R 3,119,775 1/1964 Wilsmann et a]. 233/46 R3,244,363 4/1966 Hein 233/26 X Primary ExaminerGeorge H. KrizmanichAttorney, Agent, or FirmFrederick J. McCarthy [57] ABSTRACT Knownrotating spectrophotometers have a series of cuvets arranged in a ringmember concentrically around a horizontally rotatable disc so that whenthe disc is rotated, centrifugal force mixes and transfers reagents andsamples to the cuvets. As each cuvet passes a light source, theabsorbence of each individual sample is detected and measuredphotometrically, and is converted to an electrical signal pulse.

Upon completion of the measurements it is necessary to empty the cuvetsand it is important that dispersion of the cuvet contents be avoided toprevent unsanitary and otherwise undesirable conditions. This isaccomplished in the present invention by forcing the contents of thecuvets into a concave ring shaped member attached to the cuvette ringwhere the expelled liquid is held and confined.

DEVICE FOR COLLECTING THE CONTENTS OF CUVETS IN A ROTATINGSPECTROPHOTOMETER ANALYZER The invention relates to a device forcollecting liquid from the cuvets of a rotating spectrophotometer.

In recent years, the need for rapid, automatic analytical devices hasincreased markedly, owing to the numerous microanalytical studies inbiochemical research, routine clinical testing for physicians andhospitals, enzymatic studies, and the like.

Recently, multistation analytical photometers which utilize acentrifugal field have become available for the rapid microanalysis of awide variety of liquids such as blood serum and other body fluids, foodproducts, and the like. Since numerous analysis can be performed rapidlyand simultaneously, these devices are of particular interest wherein alarge number of samples is involved or a variety of tests on one sampleis desired.

One such device which utilizes a centrifugal field in microanalyticalstudies is described in Analytical Biochemistry, 28, 545-562 (1969).This device employs the principle of doublebeam spectrophotometrywherein absorbencies of a liquid sample and a reference solution areintercompared. The system is basically a series of cuvets arrangedaround the periphery of a rotor so that when it is spun, centrifugalforce simultaneously mixes and transfers reagents and samples to thecuvets where an analysis is made spectrophotometrically. A sampleloading disc is provided which contains rows of cavities arrangedconcentrically. Reagents are placed in the inner cavities, and thesamples to be analyzed are placed in cavities at a greater radialdistance than those containing the reagents. The sample loading disc isthen indexed and positioned in the rotor with each individual reagentand sample system having a corresponding cuvet. As the rotor isaccelerated, centrifugal force moves the reagent to the cavitycontaining the sample, where they are mixed and the mixture of reagentand sample is then moved by centrifugal force through a communicatingpassage into the cuvet. The filled cuvets rapidly spin past the fixedlight beam, and the transmission of light through the cuvets, i.e.,through the samples, is measured.

Upon completion of the measurements of the samples, it is necessary toremove the liquid samples from the cuvets so that measurements can bemade on new samples. In the past, pressurized air has been employed toforce liquid from the cuvets into the housing surrounding the analyzerand exhaust devices were employed in an effort to remove the dispersedand atomized liquid. This was a difficult task and a potentialbiological and sanitary hazard was always present.

Accordingly, it is an object of the present invention to provide adevice for the removal and collection of liquid samples from a rotatingphotometric analyzer.

Other objects of the invention will be apparent from the followingdescription and appended drawings and claims.

In the Drawings FIG. 1 shows an elevational cross-section view of arotating photometric analyzer incorporating the collecting device of thepresent invention.

FIG. 2 is a partial plan view of a sample disc and cuvet ring of arotating photometric analyzer and FIG.

3 shows an isometric view of portion of the collecting device of thepresent invention.

With reference to the drawing, FIG. 1 shows in elevation a rotatingphotometric analyzer comprising a removable sample-reagent disc 10supported on a rotor 11 and suitably indexed thereto (not shown). Rotor11 is affixed to drive assembly 12 by pin 15. Drive assembly 12 isrotatably driven by way of v-belt pulley 13 attached to drive shaft 17.The portion 16 of rotor 11 is suitably of stainless steel over which isarranged a glass plate 18. The body portion 20 of sample-reagent disc 10is suitably formed of Teflon (Trademark of E. I. Dupont de Nemours) andcontains a plurality, usually about 30, of concentrically arrangedinter-connecting cavities indicated at 22. Reagent cavity 24, containsfor example a glucose reagent such as a 0.3 molar triethanolamine bufferof pH 7.5 containing 0.0004 Mol/- liter NADP, 0.0005 Mol/liter ATP,mg/liter hexokinase, 140 mg/liter glucose-6-phosphate dehydrogenase and0.004 Mol/liter MgSO The reagent, indicated at 26, upon spinning of thesample-reagent disc 10, passes into sample cavity 28, containing forexample blood serum, and both liquids pass via transfer passage 30 intoCuvette 32 located in ring member 34 which is affixed (not shown) torotor 11. Cuvette 32, and all other cuvettes, are enclosed by ringmember 34. Ring member 34 is suitably formed of aluminum. The extent ofthe reaction between the liquids in cuvette 32 is measuredphotometrically by means of light source 38 and photomultiplier 40 inaccordance with known techniques.

As shown in FIG. 1, the rotating photometric analyzer is substantiallyenclosed by metal housing 48, plastic ring shield member 51 and plasticcap member 52, which encloses sample reagent disc 10 containing cavities22.

In accordance with the present invention, and with reference to FIGS. 1and 3 in particular, a collecting ring 50 suitably made of aluminum iffixedly attached to cuvet ring member 34 and is rotatable therewith uponactuation of drive assembly 12.

Upon completion of the measurements for the liquid 33 in cuvettes 32,and while cuvet ring member 34, and attached collecting ring 50, arestill rotating, pressurized gas, e.g., forced air, is introduced viaconduit 60 into passageway 64 of drive assembly 12, conduits 66 inenclosed sample-reagent disc 10. The forced air is used to move cuvetliquid 33, previously confined within cuvets 32 and siphon arms 80, tosiphon arms 82. Due to the siphon arrangements 68, communicating viaconduits 70 with cuvets 32, the cuvet liquid 33 moves to the outersurface of cuvet ring 34. The forced air forces the cuvet liquid to theouter surface of the cuvet ring 34 where centrifugal force developed byrotation of the cuvet ring 34 causes the expelled cuvet liquid 71 to bethrown against the generally concave surface 72 of annular collectingring 50 and held by centrifugal force in a relatively narrow andconfined zone. Upon discontinuing rotation, the cuvet liquid 71 falls bygravity over restraining edge 75 into drain ring 77 from which it can beconveniently withdrawn via conduit 79 utilizing conventional pumpingmechanisms. In the device of the present invention, the air space in theannular passage is essentially static with respect to the expelled cuvetliquid since collecting ring 50 and cuvet ring 34 rotate together. Thusthe spattering and atomization of liquid, which would occur due toturbulent air conditions if collecting ring 50 were stationary,

is avoided. Spattering is further minimized by arranging the collectingring 50 such that the expelled cuvet liquid strikes the collecting ringat acute angle to the tangent of the collecting ring surface asindicated at 92.

As can be seen, dispersion and atomization of cuvet liquid is avoidedwhereby the threat of toxic and unsanitary conditions are eliminated.Also, interference with the optical system and other mechanisms of theanalyzer is avoided. Also, the device of the present invention isself-balanced in both the empty and filling conditions. Further, thedevice of the present invention is uncomplicated, inexpensive andrequires no maintenance.

What is claimed is:

1. In a rotating spectrophotometric chemical analyzer including arotating cuvet ring having an outer surface and having cuvettes incommunication with said outer surface, said cuvets being adapted tocontain liquid, the improvement for collecting liquid from the cuvetswhich comprises means for forcing the liquid in said cuvets to the outersurface of said rotating cuvet ring to enable the centrifugal forcedeveloped by said cuvet ring to separate said liquid from said cuvetring and collecting means fixedly positioned with respect to saidrotating cuvet ring and rotating therewith having a generally concaveinner surface opposite said cuvets arranged to restrain and confineliquid separated from 2. In a rotating spectrophotometric chemicalanalyzer including a rotating cuvet ring having an outer surface andhaving cuvettes in communication with said outer surface, said cuvetsbeing adapted to contain liquid, the improvement for collecting liquidfrom the cuvets which comprises conduit means communicating with each ofsaid cuvets and the outer surface of said cuvet ring and arrangedwhereby liquid is retained in said cuvets and said conduit means; meansfor applying pressurized gas to said cuvets to force the liquid in saidcuvets through said conduits to the outer surface of said rotating cuvetring to enable the centrifugal force developed by said cuvet ring toseparate said liquid from said cuvet ring; and an annular collectingmember affixed to and surrounding said cuvet ring having a generallyconcave inner surface arranged to restrain and confine the liquidseparated from said cuvet ring within said annular collecting duringrotation of said cuvet ring.

3. Apparatus in accordance with claim 2 wherein an additional collectingmember is located below said annular ring member to receive liquid fromsaid annular ring by gravity flow when said annular ring member ceasesto rotate.

1. In a rotating spectrophotometric chemical analyzer including arotating cuvet ring having an outer surface and having cuvettes incommunication with said outer surface, said cuvets being adapted tocontain liquid, the improvement for collecting liquid from the cuvetswhich comprises means for forcing the liquid in said cuvets to the outersurface of said rotating cuvet ring to enable the centrifugal forcedeveloped by said cuvet ring to separate said liquid from said cuvetring and collecting means fixedly positioned with respect to saidrotating cuvet ring and rotating therewith having a generally concaveinner surface opposite said cuvets arranged to restrain and confineliquid separated from said cuvet ring within said collecting duringrotation of said cuvet ring.
 2. In a rotating spectrophotometricchemical analyzer including a rotating cuvet ring having an outersurface and having cuvettes in communication with said outer surface,said cuvets being adapted to contain liquid, the improvement forcollecting liquid from the cuvets which comprises conduit meanscommunicating with each of said cuvets and the outer surface of saidcuvet ring and arranged whereby liquid is retained in said cuvets andsaid conduit means; means for applying pressurized gas to said cuvets toforce the liquid in said cuvets through said conduits to the outersurface of said rotating cuvet ring to enable the centrifugal forcedeveloped by said cuvet ring to separate said liquid from said cuvetring; and an annular collecting member affixed to and surrounding saidcuvet ring having a generally concave inner surface arranged to restrainand confine the liquid separated from said cuvet ring within saidannular collecting during rotation of said cuvet ring.
 3. Apparatus inaccordance with claim 2 wherein an additional collecting member islocated below said annular ring member to receive liquid from saidannular ring by gravity flow when said annular ring member ceases torotate.